What is really being questioned here? Hanmi handachi techniques were viable techniques for their time...and they still are! Almost anything that you can do standing you can do sitting! But we all know that right? Not to mention that tachi waza improves immensely by mastering suwari waza.
What Ron and David were saying is right on. Too often you see people applying the technique without true control of uke's center allowing them to harbor the misconception that they might be able to "sneak" a punch or kick in there somewhere.
The cross step while entering to prepare to apply the take down must have control of uke's center. As David said, this moves uke center around making it safe to cross in front of him WITHOUT fear of being stricken. Why, because you have moved uke's center out of the way and unbalanced them. Hopefully at this point their center is rotating and they are up on their toes.
How is that achieved, well Michael Stuempel's posts addresses that. It is all in the hand placement or grip on the wrist depending on which attack.
So the next question addresses strikes after the grab, right? Your to late!!! You have to be moving upon the initial grab...you've made a decision to attack the grabbing hand already. Any secondary strike after that is just that, secondary. If you don't have what you need to handle the primary attack then adapt and do what you can with the secondary.
I am assuming that all that are participating in this thread have been uke in this technique. How viable is it to reach down to grab someone's hand and then try to hit/kick someone? It can be done but is not very effective. Just the act of bending over to grab someone puts you too off balance to generate any power. That being the case, in the course of a true attack the attacker would have to make a decision to EITHER grab or strike. Since I am not Jackie Chan or Jet Li, I do not see myself being attacked in this fashion anytime soon!
In learning this technique from Amos Parker Sensei it was always stressed to initiate movement BEFORE uke gets a solid grip on you. This is not new. Daito Ryu stresses the same principle.
Here is a lovely exposition of shihonage techniques http://www.myaa.info/media/Parker_Embu_Shihonage.wmv